My husband gets his wheelchairs (and all other medical supplies) from the VA because he was injured while in the Navy, but I have a few suggestions.......
Quickie is a good brand of wheelchairs, although there are many others that are also good. One thing you want to check is how it folds up, in case you need to put it into a car (another reason to make sure it's light and easy to handle, in case it's you that is lifting it into a trunk of a car or onto a car carrier). Different chairs fold differently. Check to make sure your dad can handle the brakes......there are different kinds. Something else to consider is a cushion for him to sit on. My husband uses Roho cushions...........they're not cheap (neither are wheelchairs!) but they're filled with air and help prevent pressure sores.
You might want to check around to see if there is a local Paralyzed Veterans of America chapter near you. I'm not sure where you are in Maryland, but I know there's a chapter there (called the Delaware/Maryland Chapter of PVA). Our local Florida chapter keeps a warehouse of stuff like wheelchairs and walkers that people have donated, and we loan them out as needed, for free, for however long someone needs them. Not sure if the Delaware/Maryland chapter does the same, but it might be worth looking in to. Here's a link to the chapter of PVA closest to you.....you might want to give them a call, they might be able to help you locate a wheelchair or give advice on some name brands to look for:
http://www.pva.org/site/PageServer?pagename=memb_chapters_mdCheck out medical supply stores too, besides local pharmacies. You might be able to get a better chair at a med supply place. I know I'm used to personalized chairs (the VA measures the person and fits the chair to them) which you won't find at a pharmacy, but what I've seen at pharmacies are pretty standardized and kind of clunky........more options at a medical supply place I would think.
Craigs list is a good idea.........also I know I see people selling used wheelchairs in the classified ads in our local newspaper all the time, might be worth taking a look there.
Hopefully your dad won't fight you too much on this.......most people see a wheelchair as a sign of giving up on their independence.........it doesn't have to be that way.